03-03-2014, 08:29 AM
woohoo Wrote:My 6.5x45 has a capacity of 42gr and will propel a 120 class bullet to apx 2800 from a 20" at near max pressure. The range of this 6.5x43 should be 2700-2750.
That sounds about right and fits well within the parameters for a GPC (general-purpose cartridge for use in portable rifles and MGs).
Assuming your 120 grain is lead-cored, a lead-free bullet (and especially a tracer) would be longer and use up more case capacity, other things being equal, thereby presumably reducing the velocity slightly.
Incidentally, Mitch Shoffner's 6.5x40 (based on the 6.8x43 case) gets good results from the 126.5 grain Barnes LRX, which is solid copper with a plastic tip (not Geneva-friendly, but a useful indicator of performance potential).
A polymer case (which any new military rifle/MG cartridge will have to be designed for) will also have thicker walls, further reducing capacity, although that seems not to reduce performance significantly because of the greater thermal efficiency.